As sorption preparations for topical treatment of wounds materials based on activated carbon, various swelling polymers of synthetic and natural origin and silicon sorbents, such as sorbents derived from silica and silicone compounds, have been proposed.
Among the carbon preparations for wound healing Actisorb Plus (Johnson & Johnson) is particularly well-known, which is an activated carbon fiber coated with colloidal silver. Actisorb Plus has a nonspecific antimicrobial effect due to silver and the carbon sorbent can absorb pathogenic metabolites that accumulate in the wound contents. The preparation is used primarily for the healing of superficial wounds and skin defects, such as venous ulcers [Furr J. R., Russell A. D., Turner T. D., Andrews A., “Antibacterial activity of Actisorb Plus, Actisorb and silver nitrate”, J. Hosp. Infect., 1994, vol. 27(3), p. 201-208]. However, activated carbon having nanometer pore size cannot absorb large protein molecules, which include bacterial toxins and tissue degradation products.
Methods of sorption-applique treatment of purulent wounds by complex sorbent SUMS-1 (Activated charcoal+Aluminium oxide) with immobilized metronidazole [Rutkovskiy E. A., Shtofin S. G., Lubarskiy M. S., Yakushenko V. K., “Grounding for application of sorption lymphogenous methods in healing of anorectal abscess”, Lecture on IV Republican scientific practical Conference with participation of international proctologists “Functional and inflectional diseases of large intestine: surgical and therapeutic aspects. New in coloproctology” (6-7 Sep. 2001)—Minsk—2001. p. 78-79] or enzymes (nigedase and hyaluronidase) have been proposed. Due to their pronounced porous structure activated carbon sorbents absorb substances of low and medium molecular weight. Metronidazole exhibits a high sensitivity towards anaerobic microflora, which is usually seen in anorectal abscesses. However SUMS-1 has limited sorption capacity, low rates of water absorption and pathogenic proteins absorption due its structure, so that it does not have anti-inflammatory properties. The duration of the nigedase and hyaluronidase action for a surface sorption-applicative detoxification in the first phase of wound healing is small (less than 16 hours), resulting in shortened fibrinolysis and necrolytic effects that reduce the effectiveness of the therapy and increase the duration of treatment [Lubarskiy M. S., Letyagin A. Y., Gabitov V. H., Semko V. V., Povazhenko A. A., “Sorption mineral carbon preparations in purulent-septic surgery”, Russian Academy of Medical Sciences. Institute of Clinical and Experimental lymphology—Bishkek, Novosibirsk, St. Petersburg, 1994].
The disadvantage of carbon adsorbents if applied to wounds is that two to three hours after application onto a wound, they start forming a crust that prevents the outflow from the wound, and the adsorption process is greatly reduced. Part of the granules is introduced into the tissue and cannot be removed. The surface of the granules is coated with fragments of cells and protein molecules, which also reduces their adsorptive activity [Alimov M. M., Experience in application carbon sorbent in treatment complicated soft tissue wounds/Alimov M. M., Bahtiyarov O. R., Batyrov D. Sh. Sorption methods of detoxification and immune correction in Surgery: Collection of treatises. —Tashkent, 1984, p. 173-174].
Wound dressings are designed to keep the wound clean and free from contamination and also to promote wound healing, particularly in chronic wounds where there may be significant tissue loss, e.g.: hydrocolloid dressings, hydrogels, alginate dressings and others [Skorkowska-Telichowska K., Czemplik M., Kulma A., Szopa J., “The local treatment and available dressings designed for chronic wounds”, J. Amer. Acad. Dermatol., 2013, vol. 68(4), p. 117-126].
There is good evidence to suggest that hydrocolloid dressings are preferential to traditional therapies (i.e. saline gauze and antiseptics) for the treatment of pressure sores, but there may be publication bias, which may have resulted from more trials with positive results being published than those with negative results. Where topical agents have been compared with a placebo for the treatment of pressure sores there is no evidence to suggest that the active treatment has a pronounced effect on healing. Comparisons between topical agents and dressings for the treatment of pressure sores suggest that the application of a topical hydrogel more efficiently promotes the healing than that experienced with an early hydrocolloid dressing but not when compared with the improved formulation of the dressing. Comparisons between dressings were unable to show any statistically significant difference in healing rates. Topical agents were, on the whole, not found to expedite the healing of venous leg ulcers [Bradley M., Cullum N., Nelson E. A. et al., “Systematic reviews of wound care management: (2) Dressings and topical agents used in the healing of chronic wounds”, Health Technol. Assess., 1999, vol. 3(No. 17, Pt. 2)].
«Geleving» is a basis of draining sorbents with an active mechanism of sorption and comprises a polyvinyl alcohol crosslinked with glutaraldehyde. The polymer has a structure that creates an irreversible sorption capacity for purulent wounds of 14-16 g/g. To reduce the multi pathogenetic effects on the purulent wound, immobilized preparations comprising bioactive draining sorbents that provide a chemotherapeutic wound cleansing (Diotevin, Anilodiotevin) are promising. They create conditions for prolonged release of the wound medications, such as antibiotics, antiseptics, proteolytic enzymes, local anesthetics. When these are applied to richly exuding wounds and brought into contact with the wound, they discharge biologically active sorbents which swell and become a coarse, easily removable gel. Release of the preparations occurs within one day and about 60% of the administered preparations are absorbed into the wound during the first hour. Antimicrobial agents such as Dioxidine can provide suppression of gram positive, gram negative and anaerobic microflora in the wound. Proteolytic enzymes (collagenase, terrylitine) contribute to the lysis of necrotic tissue. However, if the swollen sorbent granules are not carefully removed from the wounds having complex structure, with deep pockets and cavities, there are complications in applicative sorption therapy. Closure of the wound edges and encapsulation of large amounts of sorbent granules which represent a foreign body can lead to a recurrence of the purulent process or the formation of a fistula [Goryunov S. V., Romashov D. V., Butivshchenko, I. A.; under redaction of PhD Abramov M., “Purulent surgery: Atlas”, BINOM. Laboratory of science, 2004, p. 504-506].
Also among sorbents the xerogel of methylsilicic acid—hydrophobic polymethylsiloxane is known that provides local wound detoxification due to active sorption of pathogens and low and middle molecular metabolites. Wound exudate fluid is “drained” through a capillary net of the powdered sorbent and organic substances are absorbed into its granules. By raising the pH of the wound it also potentiates the action of a specific antibiotic. Polymethylsiloxane can be used for the applique sorption with or without antibiotics immobilized on its surface. Exemplary preparations are Imosgent and Gentaxan in which the polymethylsiloxane surface is modified by gentamicin [Znamenskiy V. A., Vozianov A. F., Vozianova Zh. M. et al., Application of therapeutic preventive preparation produced on the silica based sorbents. Methodological recommendations, Kiev, 1994, p. 14]. However, in the case of hydrophobic materials, the exudate is not absorbed and spreads rapidly under the bandage which promotes skin maceration and activation of the inflammatory process in the wound [Baksa J., “Selection of wound dressings”, J. Orvisi Hetilap., 2000, vol. 141(47), p. 2549-2554].
Hydrophilic highly dispersed silica (HDS) can be used in the first phase of wound healing. Its detoxifying action is due to the ability to absorb pathogenic protein substances (up to 800 mg/g), including microbial enzymes, endo- and exotoxins and microorganisms. The surface of the silica is covered with hydroxyl groups that can bind water molecules, so it produces a pronounced dehydrating effect on the tissue that is essential for the removal of edema as part of the inflammatory process. However, silica, due to lack of porous structure, does not absorb low and middle molecular weight toxic metabolites. HDS does not show direct antimicrobial action, however, it was found that the sensitivity of pathogenic organisms to antibiotics is increased in the presence of HDS [Blitz J. P. and Gun'ko V. M. (eds.), Surface Chemistry in Biomedical and Environmental Science, Springer, 2006, p. 191-204].
Noteworthy is a combination of hydrophilic and hydrophobic sorbents, providing sorption of a wide range of substances and pathogenic microorganisms in wounds. Through a combination of hydrophilic and hydrophobic sorbents these products can provide clean wounds through a selective sorption and draining effect.
The composite wound healing preparation “Flotoxan” includes highly dispersed hydrophilic silica and hydrophobic polymethylsiloxane in a mixture with a surface-active antimicrobial substance such as ethonium [Ukrainian patent UA 32088 A, Wound healing preparation “Flotoxan” and way of its preparation, Shevchenko Y. M., Gerashchenko Viltsanyuk O. A.]. The preparation has a high antimicrobial activity and dehydrating effect, the ability to absorb and to retain proteins, bacteria and their toxins, metabolites of middle molecular weight, whereby the resorption of the mentioned substances through the wound surface is prevented. Also, due to activation of protease activity by the preparation the content of the wound shows proteolytic properties although the preparation does not contain a component with antimicrobial activity against anaerobic microorganisms.